dClass and Varnish

Reza Naghibireza.naghibi@yahoo.com

VUG 7 May 2013

Agenda

• What is dClass?• Brief history of device detection• Device classification in Varnish using

dClass• Device classification and developers• Apache DeviceMap• The future of dClass

What is dClass?

• dClass is search reversed• Search is discovery, dClass is

classification• dClass indexes searches• Searches are patterns• Patterns represent knowledge• dClass indexes knowledge

How does dClass work?

• dClass uses a handful of performance optimizations

• Algorithms == speed• Memory efficiency == speed• dClass precompiles all regex• dClass breaks out of dead input by walking the

input as it walks the pattern tree• Concise patterns == high performance

History of device detection

• User-Agent header was designed for this• Browsers, screen sizes, network speeds,

and CPU speeds all progressed at ‘relatively’ the same pace

• Mobile devices and tablets changed that• Client fragmentation led to developer

fragmentation

Server side device ‘detection’

• It is not detection, its classification!• The device classes we care most about:

– Smart phones– Tablets– Desktop browsers– Web Crawlers– Feature phones (maybe?)

• Each class has different requirements• Browser version targeting is available (think

IE)

Device ‘detection’ challenges

• Device detection used to be difficult:– Logic was messy and non performant– New devices are released every month

• dClass + Varnish is clean and performant• Apache DeviceMap (formally OpenDDR) and

other commercial offerings stay ontop of releases

• How often do you update your website? That is how often you should update your DDR!

dClass + Varnish

• The solution is completely contained within Varnish• VCL is expressive! Lots of options:

– Send device classification header to backend. Serve different views on same URL and domain.

– Redirect requests to device specific domain or rewrite to device specific URL. Can still have single backend.

– Mix and match

• Upstream caching (CDN) complicates this, may need to use cookies (or just find a better CDN…)

• Varnish can even serve device classification JSON for client side use

dClass + Varnish configuration

Source:https://github.com/TheWeatherChannel/dClass

VCL:https://raw.github.com/TheWeatherChannel/dClass/master/servers/varnish/dclass.vcl

•To update your DDR just use vcl.load and vcl.use in varnishadm (no downtime!)•Apache DeviceMap has monthly DDR updates•Vendors/Admins/SysOps, offer this to your clients!

Device classification + developers

• Device classification will simplify your code• Device classification is just another backend

parameter• It can be completely transparent to the

web stack like load balancing or caching• Projects like dClass and DeviceMap have

made device classification more accessible than ever

Apache DeviceMap

• Was born out of the OpenDDR project• Still in incubator status, so look for big

changes in the upcoming months• Have an issue with a device, tell us!• Contribute!http://incubator.apache.org/devicemap/

dClass and the future

• dClass is a powerful pattern classification engine

• Better classification leads to things like higher order reasoning and richer interactions

• webClass (http://rezsoft.org/webclass)

• Contribute!

Questions?

• I am always available for questions and support– Email: reza.naghibi@yahoo.com– LinkedIn: Reza Naghibi– Twitter: rezaberry